The Mouse Pathobiology Core will be established to provide the necessary facilities and faculty and staff expertise to support all three research projects. A major goal of the Core will be to provide expertise in mouse pathology with up-to-date proficiency in mammary gland and breast cancer pathology and the pathobiology of metastasis. Pathology support will be provided by veterinary anatomic and clinical pathologists that are Diplomats of the American College of Veterinary Pathologists. Expertise in comparative mammary gland pathology will enable appropriate interpretation and evaluation of the mouse models in the research projects and comparison to human mammary cancer. In addition, a D.V.M. postdoctoral trainee in mouse pathology will perform the mouse necropsies (autopsies), cutting and processing of tissues and evaluation of histopathology under the supervision of faculty pathologists. This will provide excellence and continuity of service for the research projects. Other services that will be available to investigators include (1) mouse clinical pathology, including a full-service hematology and clinical chemistry laboratory in the Veterinary Medical Teaching Hospital that can appropriately analyze samples from all species including mice; (2) expertise in mouse imaging, including Faxitron high resolution radiography, scintigraphy, and whole animal or organ bioluminescent and fluorescence imaging; (3) support for studies on metastasis including orthotopic implantation of tumor tissue into the mammary glands or lungs and injection of tumor cells into the left cardiac ventricle to induce bone metastasis; and (4) support for transplantation of mammary gland anlage between mice with different genetic alterations. Faculty for the Mouse Pathobiology Core will be organized from the Department of Veterinary Biosciences. Facilities will include four necropsy rooms (including one devoted to the Core) and an automated Dako immunostainer, microcopy facilities including a 10-headed microscope with video output for conferences, dedicated bioluminescent and fluorescent in vivo imaging instrumentation, digital gross and microscopic photography facilities, histomorphometry equipment including a fluorescent microscope and Bioquant Nova analysis software, mouse surgery and radiology facilities including high resolution scintigraphy in the Colleges of Veterinary Medicine and Medicine. These faculty and services will provide a unique resource to the research projects and significantly enhance the quality and validity of the research data.